I often dash more than once with Angostura, unless I have made the cocktail a few times & found it requires just the one dash - I think the natural variance between dashes is likely to have a negligible effect.

Angostura are a supremely balanced bitters IMO. If you were to use Fees Bros, you need to take caution as they have some overly strong notes (Bitter Truth can also be strong).

If I'm making something like an Old Fashioned, ill count out 5/6 drops of 'tradition aromatic' bitters or dash away with Regans or Peychauds.

After seeing it on TC a while ago, I now put pimento dram in an angostura bitters bottle - works fine for drinks requiring small amounts (but then again my homemade stuff is softer than shop brought). Grenadine is unlikely to overpower a drink so I would think that would work fine in a dasher bottle.

I agree with an earlier poster a 'light dash' & a 'hard dash' are possible with bitters bottles, IMO making a drink over & over combined with taste should dictate what you do.

With Pernod, I use an eye dropper & either count the drops or use a full load (which is 1/8 tsp in the particular dropper I have). I have recently being trying out 2 or 3 sprays of absinthe from atomiser which I found works well (I use Absente Absinthe).